Initial commit

Torque/SDK/engine/sceneGraph/windingClipper.cc

@@ -0,0 +1,127 @@
+//-----------------------------------------------------------------------------
+// Torque Game Engine
+// Copyright (C) GarageGames.com, Inc.
+//-----------------------------------------------------------------------------
+
+#include "sceneGraph/windingClipper.h"
+
+void sgUtil_clipToPlane(Point3F* points, U32& rNumPoints, const PlaneF& rPlane)
+{
+   S32 start = -1;
+   for (U32 i = 0; i < rNumPoints; i++) {
+      if (rPlane.whichSide(points[i]) == PlaneF::Front) {
+         start = i;
+         break;
+      }
+   }
+
+   // Nothing was in front of the plane...
+   if (start == -1) {
+      rNumPoints = 0;
+      return;
+   }
+
+   Point3F finalPoints[128];
+   U32  numFinalPoints = 0;
+
+   U32 baseStart = start;
+   U32 end       = (start + 1) % rNumPoints;
+
+   while (end != baseStart) {
+      const Point3F& rStartPoint = points[start];
+      const Point3F& rEndPoint   = points[end];
+
+      PlaneF::Side fSide = rPlane.whichSide(rStartPoint);
+      PlaneF::Side eSide = rPlane.whichSide(rEndPoint);
+
+      S32 code = fSide * 3 + eSide;
+      switch (code) {
+        case 4:   // f f
+        case 3:   // f o
+        case 1:   // o f
+        case 0:   // o o
+         // No Clipping required
+         finalPoints[numFinalPoints++] = points[start];
+         start = end;
+         end   = (end + 1) % rNumPoints;
+         break;
+
+
+        case 2: { // f b
+            // In this case, we emit the front point, Insert the intersection,
+            //  and advancing to point to first point that is in front or on...
+            //
+            finalPoints[numFinalPoints++] = points[start];
+
+            Point3F vector = rEndPoint - rStartPoint;
+            F32 t        = -(rPlane.distToPlane(rStartPoint) / mDot(rPlane, vector));
+
+            Point3F intersection = rStartPoint + (vector * t);
+            finalPoints[numFinalPoints++] = intersection;
+
+            U32 endSeek = (end + 1) % rNumPoints;
+            while (rPlane.whichSide(points[endSeek]) == PlaneF::Back)
+               endSeek = (endSeek + 1) % rNumPoints;
+
+            end   = endSeek;
+            start = (end + (rNumPoints - 1)) % rNumPoints;
+
+            const Point3F& rNewStartPoint = points[start];
+            const Point3F& rNewEndPoint   = points[end];
+
+            vector = rNewEndPoint - rNewStartPoint;
+            t = -(rPlane.distToPlane(rNewStartPoint) / mDot(rPlane, vector));
+
+            intersection = rNewStartPoint + (vector * t);
+            points[start] = intersection;
+         }
+         break;
+
+        case -1: {// o b
+            // In this case, we emit the front point, and advance to point to first
+            //  point that is in front or on...
+            //
+            finalPoints[numFinalPoints++] = points[start];
+
+            U32 endSeek = (end + 1) % rNumPoints;
+            while (rPlane.whichSide(points[endSeek]) == PlaneF::Back)
+               endSeek = (endSeek + 1) % rNumPoints;
+
+            end   = endSeek;
+            start = (end + (rNumPoints - 1)) % rNumPoints;
+
+            const Point3F& rNewStartPoint = points[start];
+            const Point3F& rNewEndPoint   = points[end];
+
+            Point3F vector = rNewEndPoint - rNewStartPoint;
+            F32 t        = -(rPlane.distToPlane(rNewStartPoint) / mDot(rPlane, vector));
+
+            Point3F intersection = rNewStartPoint + (vector * t);
+            points[start] = intersection;
+         }
+         break;
+
+        case -2:  // b f
+        case -3:  // b o
+        case -4:  // b b
+         // In the algorithm used here, this should never happen...
+         AssertISV(false, "SGUtil::clipToPlane: error in polygon clipper");
+         break;
+
+        default:
+         AssertFatal(false, "SGUtil::clipToPlane: bad outcode");
+         break;
+      }
+
+   }
+
+   // Emit the last point.
+   finalPoints[numFinalPoints++] = points[start];
+   AssertFatal(numFinalPoints >= 3, avar("Error, this shouldn't happen!  Invalid winding in clipToPlane: %d", numFinalPoints));
+
+   // Copy the new rWinding, and we're set!
+   //
+   dMemcpy(points, finalPoints, numFinalPoints * sizeof(Point3F));
+   rNumPoints = numFinalPoints;
+   AssertISV(rNumPoints <= 128, "MaxWindingPoints exceeded in scenegraph.  Fatal error.");
+}